[PATCH] ide-scsi: kmap scatter/gather before doing PIO
From: Stuart Hayes <Stuart_Hayes@dell.com>
The system can panic with a null pointer dereference using ide-scsi if
PIO is being done on scatter gather pages that are in high memory,
because page_address() returns 0. We are actually seeing this using a
tape drive. This patch will kmap_atomic() the pages before performing
PIO.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@elka.pw.edu.pl>
diff --git a/drivers/scsi/ide-scsi.c b/drivers/scsi/ide-scsi.c
index d80c4c9..83f062e 100644
--- a/drivers/scsi/ide-scsi.c
+++ b/drivers/scsi/ide-scsi.c
@@ -179,8 +179,18 @@
return;
}
count = min(pc->sg->length - pc->b_count, bcount);
- buf = page_address(pc->sg->page) + pc->sg->offset;
- drive->hwif->atapi_input_bytes(drive, buf + pc->b_count, count);
+ if (PageHighMem(pc->sg->page)) {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ buf = kmap_atomic(pc->sg->page, KM_IRQ0) + pc->sg->offset;
+ drive->hwif->atapi_input_bytes(drive, buf + pc->b_count, count);
+ kunmap_atomic(buf - pc->sg->offset, KM_IRQ0);
+ local_irq_restore(flags);
+ } else {
+ buf = page_address(pc->sg->page) + pc->sg->offset;
+ drive->hwif->atapi_input_bytes(drive, buf + pc->b_count, count);
+ }
bcount -= count; pc->b_count += count;
if (pc->b_count == pc->sg->length) {
pc->sg++;
@@ -201,8 +211,18 @@
return;
}
count = min(pc->sg->length - pc->b_count, bcount);
- buf = page_address(pc->sg->page) + pc->sg->offset;
- drive->hwif->atapi_output_bytes(drive, buf + pc->b_count, count);
+ if (PageHighMem(pc->sg->page)) {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ buf = kmap_atomic(pc->sg->page, KM_IRQ0) + pc->sg->offset;
+ drive->hwif->atapi_output_bytes(drive, buf + pc->b_count, count);
+ kunmap_atomic(buf - pc->sg->offset, KM_IRQ0);
+ local_irq_restore(flags);
+ } else {
+ buf = page_address(pc->sg->page) + pc->sg->offset;
+ drive->hwif->atapi_output_bytes(drive, buf + pc->b_count, count);
+ }
bcount -= count; pc->b_count += count;
if (pc->b_count == pc->sg->length) {
pc->sg++;